One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,7)(6,8)(9,10)(11,17,19,14)(12,16)(13,15)(18,23,24,21)(20,22)(25,26,28,31,29,32,35,38)(27,30,34,37,33,36,39,40)(1,2,4,6)(3,8,7,5)(9,11,13,19)(10,14,15,17)(12,18,20,24)(16,21,22,23)(25,27)(26,30)(28,34)(29,33)(31,37)(32,36)(35,39)(38,40)(10,15)(14,17)(16,22)(21,23)(27,33)(30,36)(34,39)(37,40) involution — undirected(9,12,13,20)(10,16,15,22)(11,18,19,24)(14,21,17,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.